Formation pressure-testing apparatus



March 19, 1968 R. L. DUDMAN 3,373,604

FORMATION PRESSURETESTING APPARATUS Filed Feb. 14. 1966 5 Sheets-Sheet l a :Ma Afro/wv y March 19, 1968v R. L DUDMAN Y 3,373,604

FORMATION PRESSURE-TESTING APPARATUS Filed Feb. 14, 196e 5 sheets-sheer i?.

f/W A E rf// TOR/VEV March 19. 1968 R. L. DUDMAN 3,373,604

FORMAT ION PRES SURE 'TESTING APPARATUS Filed Feb. 14, 1966 5 Sheets-Sheet 5 Foy l. 50a/maf? INVENTOR.

United States Patent O 3,373,604 FGRMATION PRESSURE-TESTING APPARATUS Roy L. Dudman, Sugar Land, Tex., assignor to Schlumberger Wcll Surveying Corporation, Houston, Tex., a corporation of Texas Filed Feb. 14, 1966, Ser. No. 527,259 6 Claims. (Cl. 7S-152) ABSTRACT F THE DISCLOSURE As exemplary of one embodiment of the invention disclosed herein, apparatus including an enclosed chamber at atmospheric pressure or a pressure lower than anticipated formation pressures and a normally-closed valve is adapted to be positioned in a full-bore packer. Thereafter, with the packer set, opening of the valve will place the well annulus below the packer in communication with the en-closed chamber and reduce the pressure in the annulus. In addition to collecting a sample of formation fluids in the chamber, where suitable pressure-measuring devices are associated with the apparatus, a so-called dry test can also be lperformed by the apparatus even though the tubing string is full.

Accordingly, as will subsequently become apparent, this invention relates to well tools; and, more particularly, to well bore apparatus for conducting various testing operations following one or more completion operations.

It is customary to employ a number of full-bore tools coupled in a string for conducting such testing and completion operations as measuring formation pressures under owing and static conditions, squeeze-cementing, acidizing and fluid-fracturing. As is typical, a string of such tools includes a full-bore packer for lpacking-off the well bore to isolate that portion of the well bore below where the packer is set from the hydrostatic pressure of the well control fluids. Above the packer, a so-called full-bore testing and completion tool (such as the one described on pages 3056-3057 of the 1960-1961 Composite Catalog of Oil Field Equipment and Services) is employed to control uid communication between the tubing string and the annulus as well as the isolated well bore portion.

Full-bore testing and completion tools such as these typically include a tubular mandrel that is telescopically disposed within a tubular housing and arranged to selectively control fluid communication between the tubing string and annulus. To utilize this tool for pressuremeasuring operations, a valve assembly carrying pressure recorders is arranged within the mandrel in such a manner that it may be selectively operated by movement of the mandrel. By opening the inner valve, communication is established between the isolated well bore portion and the tubing string. Thus, the pressure recorders on the assembly will obtain a record of the so-called shut-in formation pressure as well as the pressure as producible formation fluids are discharged into the tubing string.

The inner valve assembly is releasably secured within the mandrel of the full-bore tool shown in the Composite Catalog in such a manner that, although the tool is within a well, the valve assembly and pressure recorders may be selectively released and dispatched to the surface through the tubing string. With the inner valve assembly and recorders removed, a continuous full-opening passage is provided from the surface t-o the isolated portion of the well bore beneath the packer for conducting completion operations. If desired, the inner valve assembly and recorders may also be returned from the surface through the tubing string and relatched into position within the mandrel. Then, once the inner valve assembly is again in Patented Mar. 19, 1968 Fice place, the tool is again capable of performing its testing functions.

For example, in one typical manner of using this fullbore tool, after the packer has been set at a desired location, a perforator is lowered through the tubing string and tools into the isolated portion of the cased Well bore below the packer for perforating the casing and cement opposite a lparticular formation to gain access thereto. Then, once the perforation is opened, the perforating gun is Withdrawn and the inner valve assembly and recorders inserted into the full-bore tool. By successively opening and closing the inner valve, a series of pressure measurements are made and recorded to obtain valuable information relating to that formation for subsequent interpretation and evaluation.

It is often determined following such a test that the perforated formation zone is not productive. Similarly, it is not at all uncommon for a previously productive formation to become depleted. In either event, it is generally necessary to close-off such non-productive formations to prevent leakage of such unwanted fluids as salt water into the cased well bore.

Accordingly, regardless of whether the full-bore tool is already in position following a testing operation or must rst be set above the perforations, such non-productive formations are generally plugged by pumping a so-called cement downwardly at high pressure through the tubing string and tools into the isolated portion of the cased well bore. By conducting this operation at a sufficiently high pressure, the liquid cement will be forced into the formation through the perforations to block-off fluid communication therefrom.

As soon as a sufiicient quantity of cement is calculated to have been injected into the tubing string, it is essential that all cement remaining in the tools and tubing string be quickly removed before it has hardened. Thus, as is conventional, theI cement will be reverse circulated out of the tools and tubing string by unsetting the packer and pumping a ushing agent (such as the well control fluids, water, or the like) downwardly through the well annulus and back up the lower open end of the packer, through the other tools, and on upwardly out of the tubing string.

Once the excess cement has been removed and the cement remaining in the formation and perforations has had sucient time to harden, it is customary to test the sufficiency of the operation by performing a so-called dry test. In a typical dry test, the full-bore tool (with the removable inner valve assembly and pressure recorders in place) and packer are positioned above the pluggedoff perforations and the packer set. Once the packer is set, the inner test valve is opened to establish communication between the isolated portion of the cased well bore and the empty tubing string leading to the surface. In this manner, the full pressure in the formation behind the cemented portion will be applied against the cement plugging the formation voids and perforations since the tubing string is either at atmospheric or some relatively low pressure. Should there be a defective cementing job, the formation pressure will be sutiicient to force formation iuids through the perforations and into the tubing string. On the other hand, should no formation fluids be produced, it will be established by the pressure measurements that the cementing operation was successful and that the unwanted formation is now safely blocked olf from the well bore.

To conduct a dry test, it is essential that the tubing string either be empty or at best have only a cushion of either water at a predetermined height in the tubing string or a gas confined therein at a predetermined low pressure. In this manner, the cement plugging the formation will be exposed to an inwardly directed pressure differental of a predetermined magnitude. It will be recognized, however, that following the reverse-circulation of the cement from the tubing string, the tubing string will still be filled with the flushing liquid. Thus, before a satisfactory dry test can be conducted, it is necessary either to remove the tubing string and tools from the well to drain the tubing string or to displace the liquids therefrom by either a so-called swabbing operation or injecting a gas, such as nitrogen, under high pressure into the tubing string at the surface.

Any of these three measures will, however, be somewhat expensive. For example, if the tools and tubing string are removed to drain the tubing string, a considerable amount of valuable rig time will be needlessly expended in merely removing and immediately re-introducing them back into the well bore. Similarly, although the tools and tubing string are left in position, a swabbing operation requires a considerable amount of time to draw out a full column of liquid. Although the gas displacement method is perhaps less time-consuming than the other two methods, the quantities of inert gases usually necessarily tend to become somewhat expensive.

Accordingly, it is an object of the present invention to provide apparatus for conducting a dry test when the tubing string contains unwanted liquids without previously removing these unwanted liquids.

This and other objects of the present invention are obtained by apparatus including a sealed gas-filled chamber at either atmospheric or a predetermined pressure that is coupled to normally-closed valve means that may be dispatched downwardly through a full tubing string and uidly sealed within a full-bore tool connected to a packer. Once the apparatus is in position and the packer is set, opening of the valve means will place the isolated portion of the well bore into communication with the gas-lilled chamber.

The novel features of the present invention are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation together with further objects and advantages thereof, may best be understood by way of illustration and ex` ample of a certain embodiment when taken in conjunction with the accompanying drawings, in which:

FIG. 1 shows a typical string of full-bore well tools as these tools may appear within a well bore;

FIG. 2 is a somewhat simplified illustration of one embodiment of apparatus in accordance with the present invention as it will appear when in position within the full-bore tool shown in FIG. 1;

FIG. 3 is a schematic representation of a portion of the apparatus shown in FIG. 1; and

FIGS. 4A-4D are successive cross-sectional views showing more in detail the apparatus of the invention that is depicted in FIG. 2.

Turning now to FIG. 1, a series of typical full-bore well tools -13 are shown tandemly connected to one another and dependently coupled from the lower end of the tubing string 14 as they may appear while within a well bore 15 during the course of a completion operation. These well tools 10-13 have been somewhat simplified inasmuch as their particular structural details are not believed essential to a full understanding of the present invention. Although similar full-bore tools may be used in practicing the present invention, these tools 10-13 might well be those as shown, for example, on pages 3056-3057 of the 1960-1961 Composite Catalog of Oil Field Equipment and Services.

At the lower end of the string of tools depicted in FIG. 1, a conventional full-bore packer 13 is provided for selectively packing ol the well bore 15. A typical hydraulic hold-down 12 is coupled at the upper end of the mandrel 16 of the full-bore packer 13 to secure the mandrel against upward movement Whenever the packer is set and the pressure within the tubing string 14 exceeds the hydrostatic pressure of the control uids 17 in the well bore 15. A typical by-pass valve 11, coupled by a tubing sub 18 above the hold-down 12, is suitably arranged to be opened to facilitate shifting of the tools 10-13 within the duid-filled well bore 15 by diverting a substantial portion of the iiuids 17 through the central bore of the retracted packer 13. Connected at 'the upper end of the string of tools 10-13 is a full-bore tool 10 suitably arranged to receive either a testing assembly (not shown, but which may be that shown on the left of page 3057 of the above-mentioned Composite Catalog) or the apparatus 19 (FIG. 2) of the present invention.

The full-bore packer 13 includes the movable tubular mandrel 16 telescopically disposed within a housing 20. An elastomeric packing element 21 is arranged around the upper portion of the mandrel 16 intermediate a fixed abutment 22 thereon and a slidable frusto-conical slip expander 23. A plurality of slips 24 movably mounted around the upper end of the housing 20 are cooperatively engaged with the slip expander 23. Spring-biased drag blocks 25 are mounted around the housing 20 to secure it as the mandrel 16 is shifted downwardly until the Slips 24 have become anchoringly engaged with the casing 26.

The hydraulic hold-down 12 coupled to the upper end of the full-bore packer mandrel 16 is provided with a plurality of piston-like gripping members 27 arranged to be urged outwardly into anchoring engagement with the casing 26. Thus, when the full-bore packer 13 is set, the gripping members 27 are driven outwardly into anchoring engagement with the casing 26 to secure the packer mandrel 16 in its downward position whenever the pressure below the packer exceeds the pressure of the fluids packing element 21.

The by-pass valve 11 has an outer tubular housing 28 into which is telescoped a tubular member 29. Spaced O-rings 30 and 31 are suitably arranged around the tubular member 29 so that whenever it is shifted downwardly within the housing 28, exterior housing ports 32 are fluidly sealed to block fluid communication from the central bore of the valve 11 to the exterior thereof.

The full-bore tool 10 is basically comprised of a tubular mandrel 33 telescopically disposed within a tubular housing 34. Means subsequently to be described are provided for releasably securing the apparatus 19 (FIG. 2) of the present invention within the central bore 35 of the tubular mandrel 33. With the releasable apparatus 19 removed, a continuous full-opening passage is provided from the surface to the isolated portion 36 of the well bore 15 beneath the full-bore packer 13 for conducting various completion operations. The upper end of the mandrel 33 is connected to the lower end of the tubing string 14 and the lower end of the housing 34 is connected to the tubular member 29 of the by-pass valve 11.

The mandrel 33 is movably connected to the tubular housing 34 by inwardly projecting, opposed lugs 37 that are cooperatively received and confined within a particularly arranged slot system 38 (FIG. 3) formed in the periphery of the mandrel. Thus, whenever the packer 13 is set, it holds the tool housing 34 stationary and the mandrel 33 is moved relative thereto by manipulating the tubing string 14. By manipulating the mandrel 33 in a particular manner, various portions of the slot system 38 are selectively brought into alignment with the lugs 37 to establish certain operating positions to be subsequently described.

As illustrated by the developed view in FIG. 3, the slot system 38 in the periphery of the mandrel 33 is cornprised of a circumferential slot 39 with longitudinal slots 40 (only one being shown) extending downwardly therefrom on opposite sides of the mandrel. The lower end of each of these longitudinal slots 40 is terminated by a transverse slot 41 which extends a short distance to the left. Partway down each longitudinal slot 40, another transverse slot 42 is extended downwardly to the left and terminated by an upwardly directed end.

Thus, it will be appreciated that the mandrel 33 may be placed into any one of three longitudinally spaced positions relative to the housing 34 as established by the vertical spacing of the slots 39, 42 and 41. Moreover, whenever the circumferential slot 39 is aligned with the fixed housing lugs 37, the mandrel 33 is in its lowermost position relative to the housing 34 and is also free to rotate relative thereto for a purpose to be subsequently explained. Whenever the mandrel 33 is in its most elevated position, the lowermost slots 41 are aligned with the fixed housing lugs 37 and lateral ports 43 in the mandrel are registered with lateral ports 44 (FIG. 1) through the housing 34. In either of the two lower longitudinal positions of the mandrel 33, O-rings 45 and 46 around the mandrel above and below the ports 43 iluidly seal the mandrel to the housing 34 to block this uid communication.

Turning now to FIG. 2, a somewhat schematic representation of one embodiment of the apparatus 19 of the present invention is shown as it will generally appear when in position in the mandrel 33 of the full-bore tool 10. Inasmuch as the other tools 11-13 will be in the same positions depicted in FIG. 1, only the full-bore tool has been shown and many minor constructional details of the tool 10 and apparatus 19 have been omitted to better illustrate the more important elements of the apparatus. Should particular details be desired, howeverthe apparatus 19 has been shown in more detail in the successive views of FIGS. 4A-4D. In these successive views, the same reference numerals described with respect to FIG. 2 have been used.

The apparatus 19 of the present invention is basically comprised of an elongated central tubular member 47 having selectively operable valve means 48 on its lower end for controlling fluid communication into the tubular member, latching means 49 for releasably connecting the apparatus in the bore 35 of the mandrel 33 of the fullbore tool 10, and an enclosed chamber 50 in fluid communication with the central tubular member. As will be subsequently explained in greater detail, once the apparatus 19 has been latched and fluidly sealed in position within the mandrel 33 of the full-bore tool 10, it will be carried by the mandrel as it is moved into its various positions as determined by the slot system 38.

The selectively operable valve means 48 is arranged in such a manner it will be opened whenever the mandrel 33 is shifted into its lowermost position to bring the housing lugs 37 into the circumferential slot 39. In the other two positions of the mandrel 33 relative to the housing 34, the valve means 4S is closed to b-lock fiuid communication through the central tubular member 47. To accomplish this, the lower end of the central tubular member 47 is closed by a transverse barrier 51 and the upper end of a sleeve 52 is slidably mounted thereon. Lateral ports 53 and 54 are respectively arranged in the sleeve 52 and tubular member 47 to move into registry with one another whenever the tubular member is moved downwardly relative to the sleeve. O-rings 55 and 55 spaced above and below the tubular member ports fluidly seal the members 47 and 52 so that unless the ports 53 and 54 are in registry, there is no communication into the central tubular member. A compression spring 57 between opposed shoulders on the members 47 and 52 maintains the ports 53 and 54 normally displaced.

On the lower end of the valve sleeve 52, means, such as a pair of opposed keys 58 that are biased outwardly by springs 59, are provided to releasably secure the sleeve to the tool housing 34. Thus, with the apparatus 19 releasably latched into the mandrel 33, as the mandrel is being shifted toward its lowermost position (as determined by the circumferential slot 39), the keys 58 will enter and become engaged within complementary notches in an inwardly directed annular shoulder 60 around the lower end of the central bore 61 of the housing 34.

Notches 62 in the outer edges of the keys 58 are so shaped that whenever they are properly aligned therewith, the keys will be urged outwardly by the springs 59 and interlocked with the annular shoulder 60.

When the keys 58 are engaged with the annular shoulder 60, the valve sleeve 52 is secured against further downward travel relative to the tool housing 34 as the mandrel 33 and central tubular member 47 continue to move downwardly. Continued downward travel of the central tubular member 47 in relation to the now-secured valve sleeve 52 will subsequently bring the inner ports 54 into registry with the outer ports 53 in the sleeve fby the time the circumferential slot 39 has |become aligned with the lixed housing lugs 37.

Once the keys 58 have been interlocked on the annular shoulder 61), the conguration of the notches 62 and the bias of the springs 59 will secure the valve sleeve 52 from shifting upwardly until a suicient upward force is applied to cam the keys inwardly against the bias of the springs. Thus, once the keys 58 are engaged with the annular housing shoulder 6), by pulling the mandrel 33 upwardly a short distance (i.e., to bring the housing lugs 37 into the slots 42), the ports 54 in the central tubular member 47 will be shifted out of alignment with the sleeve ports 53 without releasing the now-stationary sleeve 52. On the other hand, when the mandrel 33 is returned to its lowermost position (as seen in FIG. 2), the ports 53 and 54 are again alined to re-establish uid communication through the central tubular member 47.

Accordingly, once the keys 58 are secured, the ports 53 and 54 may be opened and closed at will by simply shifting the mandrel 33 downwardly and upwardly between slots 39 and 42. The keys 58 are released by pulling the mandrel 33 upwardly (beyond the slot 42) a s-utcient distance to allow the inclined lower surfaces in the notches 62 to cam the keys inwardly against the springs 59 and free them from engagement with the annular housing shoulder 60.

At the upper end of the apparatus 19, a sealed chamber 50 is provided. The sealed chamber 50 is preferably comprised of a number of tubular members 63 and 64 that, as will be subsequently described, are connected to one another to provide a particular volume. The upper end of the chamber 50 is closed and its lower reduced end 65 is extended into the central tubular member 47 and fluidly sealed therein by -an O-ring 66. Valve means 67, such as a threaded valve lbody 68 having an O-ring 69 around the forward end adapted to sealingly engage a complementary seat 70, are provided to close-olf a fluid passage 71 between the interior and exterior of the chamber 50. Thus, while the apparatus 19 is still at the surface, gas can be introduced into the chamber 50 through the fluid passage 71 to pre-charge the chamber at a predetermined pressure. One the other hand, the chamber 50 can be left at atmospheric pressure if desired and the valve 67 closed.

It will be appreciated, of course, that the apparatus 19 needs only to be capable of being selectively latched into position within the mandrel 33 when only a single dry test is to be performed. Where subsequent operations are to be conducted, however, it is preferable to provide means for selectively releasing the apparatus 19 so that further testing and completion operations can be conducted. By providing this capability, the tools 10413 may be moved to a different position in the well bore 15 or, should the first dry test prove that the first cementing operation has been unsuccessful, the apparatus 19 can be removed and additional cement injected to attempt to tightly plug the perforations 72 and formation 73 (FIG. 1). Accordingly, to make it compatible with the full-bore tool as described in the aforementioned Composite Catalog, the apparatus 19 is releasably secured to the tool by selectively operable latch means 49.

The central tubular member 47 of the apparatus 19 is extended upwardly into the central bore 35 of the mandrel 33 and terminated by a reduced portion 74 having an intermediate enlarged shoulder 75. A bearing 76 is disposed around the reduced portion 74 of the central tubular member 47 and rested on the upper face of the shoulder 77. A plurality of threads 78 are formed around the uppermost end of the reduced portion 74 of the central tubular member 47 for a purpose to be subsequently described.

A sleeve member 79 is rotatively disposed around the upper end portion 74 of the central tubular member 47, with the lowermost end of the external sleeve resting on the upper face of the bearing 76. The external sleeve member 79 is free to rotate relative to the central tubular member 47, but is prevented from moving in either longitudinal direction by an inwardly directed shoulder 80 around its lower end that is disposed underneath the outwardly directed shoulder 75 around the central tubular member.

Longitudinal slots 81 are provided in opposite sides of the upper end of the external sleeve member 79 for receiving pivotally mounted latches 82 therein. Means, such as springs 83, are provided to normally bias the upper ends of the latches 82 radially outwardly into a complementary annular recess 84 formed in the upper end of the central bore 35 of the mandrel 33. To support the apparatus 19, the external sleeve 79 is enlarged, as at 85, and arranged to fit over a complementary shoulder 86 in the bore 35 of the mandrel 33 below the annular recess 84 therein. A longitudinal spline or key 87 on the enlarged sleeve portion 85 is arranged to be received within a complementary slot through the shoulder 86 to co-rotatively secure the external sleeve 79 relative to the mandrel 33. Accordingly, once the apparatus 19 is in position, it will be secured against longitudinal movement by the latches 82 and the enlarged portion 85 and the apparatus can not rotate relative to the mandrel 33.

A longitudinal inwardly directed spline 88 is provided within the internal bore of the external sleeve member 79, with this spline being slidably received in a substantially longer spline groove 89 formed in the periphery of a tubular jack-screw member 90 received in the external sleeve member. Internal threads at the lower end of the jack-screw member 90 are threadedly engaged with the threads 78 at the upper end of the central tubular member 47. Another sleeve 91 is slidably received in the uppermost end portion of the jack-screw member 90 and has its upper end so enlarged as to provide an upwardly diverging tapered surface 92 normally above the lower ends of the pivotal latches 82. A spring 93 between the upper end of the jack-screw member 90 and a shoulder 94 on the release sleeve 91 normally biases the release sleeve upwardly to normally maintain the tapered surface 92 a slight distance above the inwardly projecting ends of the latches 82. Co-engaging shoulders 95 and 96 on the release sleeve 91 and jack-screw member 90 prevents the separation of the members by the spring 93.

Accordingly, when it is desired to release the apparatus 19 from its position as shown in FIG. 2, the mandrel 33 is appropriately manipulated so as to bring its circumferential slot 39 into alignment with the housing lugs 37. It will be realized that once the circumferential slot 39 is in alignment with the housing lugs 37, the mandrel 33 is free to be rotated with respect to the tool housing 34. In this position of the mandrel 33 relative to the housing 34, a thrust bearing 97 around the mandrel is brought into engagement with the upper end of the housing to carry the downward thrust as the tubing string 14 is rotated.

As the mandrel 33 is rotated, the torque is transmitted through the key 87 in the shoulder 86 to rotate the external sleeve member 79 as well. Inasmuch as the external sleeve member 79 is held against longitudinal travel by the interengagement of the bearing 76 and shoulders 77 and 80, as the sleeve member rotates, the splines 88 will rotate the jack-screw member downwardly along the threads 78.

It will also be recalled that whenever the circumferential slot 39 is in alignment with the housing lugs 37, the keys 58 on the lower end of the valve sleeve 52 are coengaged within slots in the inwardly projecting housing shoulder 60 in such a manner that the central tubular member 47 is secured against rotation with respect to both the housing 34 and the mandrel 33. Thus, as the jack-screw member 90 is rotated, the threads at the lower end of this member will be threaded downwardly on the threads 7 8 at the upper end 74 of the central tubular member 47. By virtue of the interlocked shoulders and 96, downward travel of the jack-screw member 90 will carry the release sleeve 91 downwardly to bring the tapered portion 92 at its upper end downwardly and into engagement with the inwardly projecting ends of the pivotal latches 82. It will be appreciated, of course, that as the tapered surface 92 moves downwardly and into engagement with their ends, the latches S2 will be cammed radially inwardly to release their upper ends from the annular recess S4 in the mandrel 33. Thus, once the jackscrew member 90 is threadedly rotated to its lowermost position (with respect to the threads 78 on the upper reduced end 74 of the central tubular member 47), the latches 82 will be retracted from within the recess 84 and the entire apparatus 19 will be freed for movement upwardly with respect to the mandrel 33.

Accordingly, by providing flow-retarding means, such as swab cups 98 on the upper end of the chamber 5t), by moving the full-bore tool 10 into its reverse-circulating position (slots 41) after the apparatus 19 is freed, it may be pumped out of the mandrel 33 upwardly through the tubing string 14 and recovered at the surface of the ground. Moreover, a retrieving tool (not shown) can be lowered on a wireline and secured over a fishing neck 99 at the upper end of the test chamber 50 to pull the freed apparatus 19 upwardly through the tubing string 14.

Turning now to the operation of the present invention. Assuming that the tools 10-13 (as shown in FIG. 1) have just completed a typical cementing operation in the formation 73, it will be appreciated that the tubing string 14 and the tools 19-13 will be full of cement and it is of the utmost necessity to remove this cement as quickly as possible to prevent it from hardening therein.

Thus, upon completion of the cementing operation, the packer 13 is unseated with the by-pass valve 11 preferably being kept closed. The well control fluids 17 are reversecirculated by pumping them downwardly through the annulus and into the lower end of the packer 13 to Flush residual cement back up and out of the tubing string 14. Circumstances may necessitate, however, that the by-pass valve 11 be opened where the packer 13 cannot be readily unseated. In this instance, the reverse-circulation is 0btained by opening the by-pass valve 11 to circulate the well control uids 17 through the opened ports 32 therein.

With the cementing operation being completed, it is now necessary to determine whether the formation 73 and perforations, as at 72, are tightly sealed. Accordingly, as seen in FIG. 2, the apparatus 19 of the present invention is then dispatched from the 'surface through the tubing string 14 and releasably secured within the full-bore tool mandrel 33. If the weight of the apparatus 19 is insu'icient to move it downwardly, additional weight or force may be employed to bring it into position.

Once the apparatus 19 has been secured into position within the full-bore tool mandrel 33, it will be recognized that although the tubing string 14 is full of liquid following the reverse-circulating operation, opening of the valve ports 53 and 54 will open communication from the isolated portion 36 of the well bore 15 through the central tubular member 47 and into the chamber 50. Thus, although the tubing string 14 is full of fluids opening of the valve means 48 will impose a dierential across the plugged formation 73 and perforations 72 (FIG. l) that is equal to the formation pressure less the pressure of the gas in the chamber 50 whether this gas be at atmospheric or some other desired low pressure. In this manner, the previously described dry test will be accomplished with the apparatus 19 of the present invention without having to previously drain the tubing string 14 of Whatever liquids that have remained therein.

By arranging the chamber 50 to have a volume in the order of l l5% of the volume of the isolated portion 36 of the well bore 15, more than suf'cient expansion space will be provided to accommodate the normal expansion of the fluids in the isolated portion. Thus, upon opening of the valve ports 53 and 54, if the eementing operation has been successful, the pressure in the isolated bore portion 36 (as measured by the pressure recorders 100) will drop to substantially the initial pressure of the chamber 50 and remain at this pressure after the valve means 48 is reclosed. Conversely, if the cementing operation was not successful, the pressure recorders Q will indicate that the pressure did not drop to and remain at this low pressure and formation fluids produced from the formation 73 upon opening of the valve ports S3 and 54 may also be recovered in the chamber 50. In any event, the apparatus 19 of the present invention will now give those skilled in the art means for positively obtaining information not heretofore possible without expending considerable time, expense and eifort.

It will be realized, of course, that in conjunction with the apparatus 19 and the pressure chamber 50, a similarly arranged retrievable valve assembly (such as that shown on the very left of page 3057 in the aforementioned Composite Catalog reference) may also be employed for conventional drillstem testing operations. This valve assembly (not shown) would be adapted to be released in the same manner as the apparatus 19 already described. In this manner, this testing assembly could be positioned within the full-bore tool 10 to conduct drillstem testing operations as needed. Thus, for example after the already described cementing and dry-testing operations, the apparatus 19 of the present invention can be removed from the full-bore tool 10 and the testing assembly installed in its place. Then, after the tools 10-13 have been repositioned inthe well bore 15, a drillstem test can be conducted at a dilferent position in the well bore. Then, should it be necessary, the testing assembly can be removed and the previously described cementing and drytesting operation repeated for plugging-off and testing of the perforations just tested.

Accordingly, it will be appreciated that the present invention has provided means for greatly improving the conduct of well testing and completion operations in a new and improved manner which has not heretofore been considered. By utilizing the apparatus of the present invention, considerable expense as well as time may be saved inasmuch as once the fullebore tool has been lowered into a well bore, it and the tubing string can be left in the well until all operations have been conducted at various depths in the well. Then, once all Such work has been completed and information obtained, the string of tools and its tubing string can be retrieved with none of the needless expense or lost time experienced heretofore.

While a particular embodiment of the present invention has ,been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects; and, therefore, the aim in the appended claims is to cover all such changes and modications as fall within the true spirit and scope of this invention.

I claim:

1. Apparatus adapted for use in a well bore comprising: a tool including first and second tubular members telescoped together and movable relative to one another between first and second positions, said first tubular member being adapted for connection to a pipe string; packing means connected to said second tubular member for packing-off a well bore; testing means adapted for passage through a string of pipe to a position within said tool and including an enclosed chamber, valve means normally closing fluid communication into said chamber, and means iiuidly sealing said testing means relative to said tool and adapted for blocking fluid communication through said tool between a packed-olf well bore and such a string of pipe; latch means engageable with said testing means for securing said testing means relative to one of said tubular members; and means on the other of said tubular members and engageable with said valve means for selectively opening and closing said valve means upon successive movements of said tubular members between said irst and second positions.

2. The apparatus of claim 1 further including means between said latch means and said one tubular member and responsive to further movement of said one tubular member for selectively disengaging said latch means whereby said testing means can move through such a string of pipe to the surface.

3. The apparatus of claim 2 further including liow-retarding means on said testing means whereby uid ow through said apparartus into such a string of pipe will carry said testing means to the surface following disengagement of said latch means.

4. The apparatus of claim 41 further including pressure-recording means on said testing means for measuring and recording iluid pressures adjacent to said valve means.

5. The apparatus of claim 4 further including means between said latch means and said one tubular member and responsive to further movement of said one tubular member for selectively disengaging said latch means whereby said testing means can move through such a string of pipe to the surface.

6. The apparatus of claim 5 further including Elow-rctarding means on said testing means whereby liuid tlow through said apparatus into such a string of pipe will carry said testing means to the surface following disengagement of said latch means.

References Cited UNITED STATES PATENTS 2,793,524 5/1957 Badger 73-l55 X 2,846,876 8/1958 Willingham 73-152 2,978,046 4/1961 True 175--233 RICHARD C. QUEISSER, Primary Examiner.

J. W. MYRACLE, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No. 3,373,604 March 19, 1968 Roy L. Dudman It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading Lo the printed specification, lines 3 and 4, "assigner to Schlumberger Well Surveying" should read assigner, by mesne assignments, to Schlumberger Technology Column 6, line 57, l'One" should read On Column 7, line 60, "prevents" should read prevent Signed and sealed this 2nd day of September 1969.

(SEAL) Attest:

Edward M. Fletcher, Jr. WILLIAM E. SCHUYLER, JR.

Attesting Officer Commissioner of Patents 

